United Kingdom grocer Tesco walks into a storm over equal pay

Legal proceedings have begun in the first equal pay claims against Tesco in what could become the largest ever equal pay challenge in United Kingdom history, which could cost the retail giant £4 billion to compensate workers.

Law firm Leigh Day says it is suing Tesco on behalf of almost 100 shop assistants who earn up to £3 per hour less than the company's, mainly male, warehouse workers, The Guardian reports.

On Wednesday, Leigh Day, a law firm said that mainly male staff working at the distribution centers were being paid considerably higher wages than its largely female work force at stores.

The company also believes the case could lead to Tesco facing a bill of up to £4 billion in compensation - and hopes it will result in store staff being paid more fairly in the future.

The firm said it has been approached by more than 1,000 people either now or formerly employed by Tesco.

It said the underpayment of workers could apply to more than 200,000 Tesco employees, with estimated pay shortfalls that could reach £20,000.

The law firm has already started to submit claims on behalf of clients through ACAS conciliation service, the first state in what will become an Employment Tribunal process.

According to the claim, Tesco warehouse staff earn from about £8.50 an hour to more than £11, while store staff earn about £8 an hour in basic pay.

The supermarket chain has defended itself and said it had taken the necessary steps to ensure all staff were paid "fairly and equally" but Lee insisted the issue had been allowed to linger on for over three decades.

"We are unable to comment on a claim that we have not received", a spokeswoman said.

At the same time, Greg Clark the Business Secretary of Britain said he was surprised by the size of the claim made against Tesco.

A Tesco spokesman said: "We work hard to make sure all our colleagues are paid..."

Many in the gig economy, where people tend to work for multiple firms without fixed contracts, operate on a self-employed basis, entitling them to only basic protections such as health and safety.

The Asda case involves almost 20,000 shopworkers and the most recent ruling backed their right to compare their jobs to those of their mostly male colleagues working in distribution centres.

"What we needed to see was a serious extension of rights to workers and a serious proposal on government enforcement of employment law, not just a consultation on the topic".